Before, during and after paradoxical sleep deprivation, field potentials, evoked in the CA1 region and in the fascia dentata of the hippocampus by means of paired pulse stimulation, were measured. Paradoxical sleep deprivation was applied for 3 days, using the platform and the pendulum technique. No changes were observed on evoked field potential amplitude, population spike or paired pulse depression during and after the deprivation period. These results suggest that the neuronal excitability in the rat hippocampus, measured with the evoked potential technique, does not change as a result of paradoxical sleep deprivation.